Ab initio analysis of a vacancy and a self‐interstitial near single crystal silicon surfaces: Implications for intrinsic point defect incorporation during crystal growth from a melt

Abstract

AbstractThe microscopic model of the Si (001) crystal surface was investigated by first principles calculations to clarify the behavior of intrinsic point defects near crystal surfaces. A c(4 × 2) structure model was used to describe the crystal surface in contact with vacuum. The calculations show lower formation energy near the surface and the existence of formation energy differences between the surface and the bulk for both types of intrinsic point defects. The tetrahedral (T)‐site and the dumbbell (DB)‐site, in which a Si atom is captured from the surface and forms a self‐interstitial, are found as stable sites near the third atomic layer. The T‐site has a barrier of 0.48 eV, whereas the DB‐site has no barrier for the interstitial to penetrate into the crystal from the vacuum. Si atoms in a melt can migrate and reach at the third layer during crystal growth when bulk diffusion coefficient is used. Therefore, the melt/solid interface is always a source of intrinsic point defects.